Dihydrocodeine is a centrally acting narcotic analgesic agent with actions qualitatively similar to those of codeine. The compound is 4,5-alpha-epoxy-3-methoxy-17-methylmorphinan-6-alpha-ol. The preparation of dihydrocodeine and its pharmaceutically acceptable acid addition salts are described in, for example, Stein, Pharmazie, 10, 180 (1955), and Merck Index, (Ninth Edition) Entry No. 3148 (1976). Ibuprofen is an anti-inflammatory agent and has also been recommended for the relief of pain in man and animals. The compound is 2-(4-isobutylphenyl)propionic acid and it is described, together with its pharmaceutically acceptable salts, in, for example, U.K. Patent Specification No. 971,700.
This invention provides a combination of these two agents. The combination provides an analgesic effect greater than that obtained by increasing the dose of either constituent administered alone. The adverse effects produced by such combination are considered to be less than those produced by an equi-analgesic dose of one of the constituents.